1. Field of the Invention
The present invention relates to a medical instrument that can obtain a tissue sample. More particularly, the invention relates to a biopsy needle.
2. Description of the Background Art
In the treatment of disease or pathological conditions it is often necessary to examine a sample of tissue to detect pathological changes in order to accurately diagnose and render proper treatment. In many instances, a knowledge of the exact cytoarchitecture of the tissue is critical to diagnosis of the specific pathological condition. When such tissue samples are removed by use of an aspirating needle such as that disclosed is U.S. Pat. No. 3,595,217 to Rheinfrank, the relational aspects of tissue substructure and infrastructure are not maintained.
There is a growing need for a device capable of obtaining brain tissue samples, for example, which samples retain the relational aspects of the brain tissue architecture. Biopsies of brain tissues are often performed for the diagnosis and localization of peripherally located brain tumors, infectious diseases, such as viral infections, including herpes simplex of the temporal lobe, Acquired Immune Difficiency Syndrome with toxoplasmosis, SSPE (Subacute sclerosing panencephalitis), neurolipidoses (storage diseases) and Alzheimer's disease. Accurate diagnosis in disease states such as those cited depend on the examination of brain tissue obtained by biopsy. The accuracy of the diagnosis will often depend upon preservation in the tissue sample of the relational aspects of the tissue architecture.
Alzheimer's disease is considered one of the most pressing problems in the 1980s, being the fourth largest cause of death in the United States. Based on pathological evaluations, it is estimated that half of all the patients in the United States with dementia have untreatable Alzheimer's disease. On the other hand, biopsy for prognosis information is important. Ten to 20 percent of all dementias or 20-40% of the remaining 50% can be successfully treated if diagnosed correctly. An accurate tissue biopsy will detect these treatable cases and be efficacious.
The neuropathologist uses paraffin embedding and paraffin microtome sectioning and frozen sectioning. Using various techniques, multiple stains according to the cellular material of interest are used for study.
The study is examined grossly under the light microscope (.times.40, .times.100, .times.400, .times.1000); changes of the neurons, fibrous connective tissue, glia, and vascular structures are observed. Nerve cell loss is important. Abnormal interneuronal material can indicate abnormal stored material: (1) neurolipidoses (ganglioside--Tay Sachs disease, Sphingomyelin--Neimann-Pick disease); (2) degeneration processes (senility pigment--lipofuscin, Alzheimer's neurofibrillary degeneration, Parkinson's disease--Lewy bodies and various viral inculsion bodies, e.g., SSPE, rabies).
Special techniques involve transmission electron microscopy, histoenzymological examinations of fresh brain and immunostaining using peroxidase antibodies.
Tissue lesions can be demonstrated by hemorrhages, atrophy, necrosis, cerebral edema, demyelination, inflammatory lesions, and connective tissue and vascular changes. Artifacts caused by unnecessary "rough handling" of brain tissue as demonstrated by biopsy suctioning, biopsy crushing, biopsy stretching, and biopsy ripping can erroneously cause hemorrhages, cerebral swelling, vascular injury and cell injury and interfere with diagnostic accuracy.
The brain biopsy information is correlated with clinical data and ancillary investigations.
A number of devices have been developed to obtain biopsy of tissue from individuals from areas such as the brain. Biopsy cannulas are often used by neurosurgeons, in some cases with the aid of fluoroscopy, computerized tomography, Magnetic Resonance Imaging, or ultra-sonography. Among the devices which were available prior to the present invention are a cannula which uses suction by a syringe to obtain a biopsy; a device in which forceps protrude from a cannula to obtain a sample, and are withdrawn; and a device which comprises a spiral cutting tip in a cannula to obtain biopsy samples. In devices such as the foregoing examples, the samples are traumatized, significantly affecting the quality and accuracy of the pathologic review. Suction of brain tissue into a needle disrupts the relational architecture of the tissue and may also disrupt the cytoarchitecture, as will compression caused by forceps or the grinding action of a spiral cutting edge. In addition, the trauma caused by removal of tissue samples by devices such as those described often leads to hemorrhage in the area from which the tissue sample was removed and causes protracted recovery of the patient.
Other biopsy devices have been devised which operate along principles described above. For example, U.S. Pat. No. 4,461,305 discloses an automated biopsy device which has a rotary mounted cutting blade which severs the tissue for extracting biopsy tissue from the female uterine cervix. A biopsy device developed to primarily obtain endocervical canal tissue samples was disclosed in U.S. Pat. No. 4,243,048, which has a non-metal "nose cone" which provides a guiding protuberance and a hollow tubular member telescopically fitted on the shaft which has an annular cutting element on the distal end and a hollow inner chamber which receives the tissue specimen. U.S. Pat. No. 3,590,808 discloses a biopsy device for use in the gastrointestinal tract in which a tissue sample is drawn into the hollow end of the device by vacuum and a pneumatically operable knife severs the biopsy sample. U.S. Pat. No. 3,173,414 discloses a combination of a biopsy probe and endoscope which utilizes a suction pump to draw in the severed tissue sample.
Examples of needle biopsy devices such as are shown in U.S. Pat. No. 2,198,319 and U.S. Pat. No. 3,001,522 disclose needles which are sharpened to sever the tissue and provide space within the shaft of the needle for storing the selected tissue and which may incorporate a gripping mechanism. U.S. Pat. No. 4,600,014 discloses a transrectal prostate biopsy device which is an improvement on the Travenol TRU-CUT.RTM. biopsy needle.
It is an object of the present invention to provide a biopsy device for obtaining biopsy samples from tissues, and preferably from brain tissue, wherein the tissue removed from the individual retains the relational aspects of the tissue substructure and architecture. It is a further object of the present invention to devise a biopsy device which is capable of removing a tissue sample for maximally accurate pathological examination and be capable of minimizing cerebral injury, swelling, or arterial vessel injury, and subsequent blood clot formation.